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Hello All, I have just purchased an extractor fan to fit in my Utility Room and trying to understand the accompanying wiring diagrams.
The unit has an integral Humidistat and Timer.
The 2x wiring options they show are as per drawings attached but I can't understand why, in Diag A, it shows the Humidistat and Timer are disabled when the wiring is basically the same as Diag B but without the switching (or am I not understanding/missing something?)


Hope someone can advise please.extractor fan wiring.jpg
 
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Pete999

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Arms
Esteemed
I think dia A is just showing you the basics of how the fan works, the second Dia is showing how the timer and Humidistat is incorporated in the installation, along with the isolation switch, Best option will be to get an Electrician to wire and certify this work. I assume this fan is to be installed in a room containing a Bath or Shower, and will require RCD protection and notification.
 

telectrix

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Mentor
Arms
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I think dia A is just showing you the basics of how the fan works, the second Dia is showing how the timer and Humidistat is incorporated in the installation, along with the isolation switch, Best option will be to get an Electrician to wire and certify this work. I assume this fan is to be installed in a room containing a Bath or Shower, and will require RCD protection and notification.
trhink OP sed utility room. but diag. B seems the one to follow. don'tforget the pointless 3A fuse.
 
T

Toneyz

What is the existing wiring assuming that there was an existing fan? I would stick with diagram A as you don't really need the fan to come on with the utility light.
 
  • Thread Starter Thread Starter
  • #7
yes thats correct, I only need the fan to come on when the humidistat detects humidity and stay on until it detects its clear
 
T

Toneyz

yes thats correct, I only need the fan to come on when the humidistat detects humidity and stay on until it detects its clear
Then if you don't want it to come on with the utility light it is DIAGRAM A.
 

Simon47

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Arms
Esteemed
Diagram A has the switched live input (SL) connected to live - so it will run all the time there's power. If you omit the link so nothing is connected to the SL then it will probably just run on the humidistat - however reliable or otherwise that is.
I mention reliability because I've seen comments in various places that humidistats don't work well. At the moment, we've got really high humidity & temperature - so the fan is likely to run all the time. But adjust it for that, and it won't switch on when outside temperatures are lower and so humidity indoors will be lower as well.
If you connect the SL input to the light as per Dia B then it will probably run when the light is on (with timer run-on), plus when the humidity is high.
 

pirate

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Arms
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Pointy fuse
:

Pointless fuse
:

OK, Tel?
 
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